Memory system

ABSTRACT

A memory system is provided. The memory system includes a memory area configured to include a plurality of memory cells; a driving area configured to drive the memory cells; and a control area configured to supply a standby current to the memory area before the memory area records data; a plurality of word lines is crossing to a plurality of bit lines via the plurality of memory cells; and wherein each of the memory cells includes a memory layer, a magnetic fixed layer, an intermediate layer including a non-magnetic material provided between the memory layer and the magnetic fixed layer, a top electrode provided over the memory layer, a bottom electrode provided over the magnetic fixed layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/220,832, filed Jul. 27, 2016, which is a continuation of U.S.application Ser. No. 14/399,268, filed Nov. 6, 2014, now Patent No.9,424,903, which is a national stage of International Application No.PCT/JP2013/001377, filed Mar. 6, 2013, which claims priority to JapaneseApplication No. 2012-112424, filed May 16, 2012, the disclosures ofwhich are hereby incorporated herein by reference.

BACKGROUND

The present application generally relates to a memory system.

In an information processor such as a computer, a DRAM (Dynamic RandomAccess Memory) with high density that is operated at high speed iswidely used.

However, the DRAM is a volatile memory where information is erased whenthe power is turned off. So, a non-volatile memory where information isnot erased is needed.

As a candidate of the non-volatile memory, a magnetoresistive randomaccess memory (MRAM) where information is recorded by magnetization of amagnetic body is focused on and is under development.

A method of recording to the MRAM includes a method of reversingmagnetization by current magnetization or a method of reversingmagnetization by directly implanting spin-polarized electrons into arecording layer (for example, see Patent Document 1).

As the method, spin implantation magnetization reversal is focused onbecause a record current can be decreased as the device size getssmaller.

Furthermore, in order to miniaturize the device, a method of using aperpendicular magnetization film where a magnetization direction of amagnetic body is directed to a perpendicular direction is studied (forexample, see Patent Document 2).

Non-Patent Document 1 discloses a reversal time equation of a spinimplantation magnetization reversal element using a perpendicularmagnetization film.

Patent Document 1: Japanese Patent Application Laid-open No. 2004-193595

Patent Document 2: Japanese Patent Application Laid-open No. 2009-81215

Non-Patent Document: R. H. Koch et al, Phys. Rev. Lett. 92, 088302(2004)

SUMMARY Problem to be Solved by the Invention

However, by the reversal time equation show in the Non-Patent Document1, the spin implantation magnetization reversal element using theperpendicular magnetization film may prolong the magnetization reversaltime as compared to the spin implantation magnetization reversal elementusing no perpendicular magnetization film.

An object of the present technology is to solve the problem in the caseof using the perpendicular magnetization film and to provide a memoryapparatus capable of operating at high speed with less current.

In addition, in the memory apparatus capable of operating at high speedwith less current, another object is to inhibit an amplitude of areadout signal from decreasing.

Means for Solving the Problem

In order to solve the problem, according to the present technology, thememory apparatus is configured as follows:

The memory apparatus according to the present technology includes amemory device having: a layer structure at least including a memorylayer where a direction of magnetization is changed corresponding toinformation, a magnetic fixed layer where the direction of themagnetization is fixed, and an intermediate layer made of a non-magneticbody disposed between the memory layer and the magnetic fixed layer;current being capable of flowing in a lamination direction of the layerstructure.

The memory apparatus also includes a wiring for supplying the memorydevice with current flowing to the lamination direction; and a memorycontrol unit for storing information by flowing standby current at apredetermined level to the memory device via the wiring to incline themagnetization direction of the memory layer from the directionperpendicular to a film surface and flowing recording current that ishigher than the standby current via the wiring to change themagnetization direction of the memory layer.

According to the present technology, the memory device is configured asfollows:

A memory device, comprising:

a layer structure at least including a memory layer where a direction ofmagnetization is changed corresponding to information, a magnetic fixedlayer where the direction of the magnetization is fixed, an intermediatelayer made of a non-magnetic body disposed between the memory layer andthe magnetic fixed layer, and a cap layer; current being capable offlowing in a lamination direction of the layer structure;

in the memory layer,

the first ferromagnetic layer, the connecting layer and the secondferromagnetic layer are laminated in this order,

the first ferromagnetic layer is magnetically connected to the secondferromagnetic layer via the connecting layer,

the first ferromagnetic layer is in contact with the intermediate layer,

the second ferromagnetic layer is in contact with the cap layer,

one of the first ferromagnetic layer and the second first ferromagneticlayer is the in-face magnetization layer being predominant in thein-face magnetization, and the other is the perpendicular magnetizationlayer being predominant in the perpendicular magnetization, and

a connecting intensity between the first ferromagnetic layer and thesecond ferromagnetic layer via the connection layer is set such thatboth magnetizations of the first ferromagnetic layer and the secondferromagnetic layer direct to the perpendicular direction in anequilibrium state where no current in the lamination direction flows tothe memory device, and the magnetization direction of the memory layeris inclined from the perpendicular direction in a standby state wherestandby current lower than the memory device flows to the memory device.

By the memory apparatus according to the present technology, informationis stored by flowing the standby current to incline the magnetizationdirection of the ferromagnetic layer of the memory layer from thedirection perpendicular to the film surface and flowing recordingcurrent to change the magnetization direction of the memory layer.

As the magnetization direction of the memory layer is inclined from theperpendicular direction before recording, the reversal time required toreverse the magnetization and to record information can be shortened ascompared to the conventional configuration that the recording currentflows in a state that the magnetization direction is not inclined. Atthe same time, variations in the reversal time produced in theconventional configuration that the recording current flows in a statethat the magnetization direction is not inclined can be decreased.

By the memory apparatus according to the preset technology, themagnetization of the memory layer can be directed to the perpendiculardirection to the film surface in the equilibrium state where no currentflows through the memory device. If the magnetization of the memorylayer is inclined from the direction perpendicular to the film surfacein the equilibrium state, the amplitude of the readout signal may bedecreased. However, according to the present technology, the decrease inthe amplitude of the readout signal can be effectively inhibited.

By the memory device according to the preset technology, themagnetization of the memory layer directs to the perpendicular directionin the equilibrium state, by flowing the standby current, themagnetization direction of the memory layer is inclined from thedirection perpendicular to the film surface.

Effect of the Invention

As described above, according to the present technology, as compared tothe conventional configuration that simply uses the perpendicularmagnetization film, the reversal time required to reverse themagnetization and to record information can be shortened and thevariations in the reversal time can be decreased. In this way, theamount of current upon the information recording can be decreased, andthe information can be recorded in a short time. As a result, there canbe provided a memory apparatus capable of operating at high speed withless current.

In addition, in the memory apparatus capable of operating at high speedwith less current, the decrease in the amplitude of the readout signalcan be inhibited.

According to the memory device of the present technology, themagnetization of the memory layer directs to the direction perpendicularto the film surface in the equilibrium state, and by flowing the standbycurrent, the magnetization direction of the memory layer is inclinedfrom the direction perpendicular to the film surface.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 A schematic perspective view of a memory apparatus of anembodiment.

FIG. 2 A cross-sectional view of the memory apparatus of the embodiment.

FIG. 3 A plan view of the memory apparatus of the embodiment.

FIG. 4 An explanatory view (cross-sectional view) about a schematicconfiguration of a prior art memory device (STT-MRAM) where amagnetization direction is perpendicular to a film surface.

FIG. 5 A schematic configuration (cross-sectional view) of a prior artmemory device.

FIG. 6 A schematic configuration (perspective view) of a memory layer inthe prior art memory device.

FIG. 7 Explanatory views of a memory device according to the firstembodiment.

FIG. 8 A conceptual diagram between current flowing in a laminationdirection of the memory device and a time change of perpendicularcomponents (mz) of magnetization Mi and magnetization Mp.

FIG. 9 A block diagram showing an overall configuration of the memoryapparatus according to the first embodiment.

FIG. 10 An explanatory view for a procedure for driving bit linesaccording to the embodiments.

FIG. 11 Explanatory views of a memory device according to the secondembodiment.

FIG. 12 Diagrams showing a time change of perpendicular components ofmagnetization of a memory device in the prior art and magnetization(magnetization Mi) of the memory layer of the memory device according tothe embodiment.

FIG. 13 An explanatory view for a procedure for shortening a recordingtime.

FIG. 14 Views showing an application of the memory device(magnetoresistive effect device) according to the embodiment to acombined magnetic head.

DETAILED DESCRIPTION

The embodiments of the present technology will be described in thefollowing order.

-   <1. Schematic Configuration of Memory Apparatus according to    Embodiment>-   <2. Memory Devices in Prior Art and Related Art>-   <3. Summary of Memory Device according to Embodiment>-   <4. First Embodiment>-   <5. Second Embodiment>-   <6. Simulation Results>-   <7. Procedure for shortening Recording Time>-   <8. Alternative Embodiment>    <1. Schematic Configuration of Memory Apparatus According to    Embodiment>

Firstly, a schematic configuration of a memory apparatus according to anembodiment will be described.

Schematic views of the memory apparatus according to the embodiment areshown in FIG. 1, FIG. 2 and FIG. 3. FIG. 1 is a schematic perspectiveview, FIG. 2 is a cross-sectional view, and FIG. 3 is a plan view.Peripheral circuits of the memory apparatus according to the embodimentare not shown.

As shown in FIG. 1, in the memory apparatus according to the embodiment,there are disposed memory devices 3 (STT-MRAMs, Spin TransferTorque—Magnetic Random Access Memories) being capable of holdinginformation in a magnetized state at an intersection point of two typesof address wirings (for example, a word line and a bit line) orthogonalto each other.

In other words, a drain region 8, source regions 7 and gate electrodes 1that configure selection transistors for selecting memory devices 3 areformed at areas separated by device separation layers 2 on asemiconductor substrate 10 such as a silicon substrate. Among them, thegate electrodes 1 also function as the address wirings (word lines)extending in a front and back direction in FIG. 1.

The drain regions 8 are formed in common to left and right selectiontransistors in FIG. 1. To the drain regions 8, wirings 9 are connected.

Between the source regions 7 and bit lines 6 disposed at an upper sideand extending in a left and right direction in FIG. 1, the memorydevices 3 having memory layers where a magnetization direction isreversed by a spin torque magnetization reversal are disposed. Thememory devices 3 are configured of magnetic tunnel junction devices (MTJdevices), for example.

As shown in FIG. 2, each memory device 3 has two magnetic layers 12, 14.As to the two magnetic layers 12, 14, one magnetic layer is amagnetization fixed layer 12 where a direction of magnetization M12 isfixed and the other magnetic layer is a free magnetization layer, i.e.,a memory layer 14 where a direction of magnetization M14 is changed.

Each memory device 3 is connected to each bit line 6 and a source area 7via each of up and down contact layers 14.

In this way, current flows to the memory device 3 through two types ofthe address wirings 1, 6 in an up and down direction (a laminationdirection). By the spin torque magnetization reversal, the direction ofthe magnetization M14 of the memory layer 14 can be reversed.

As shown in FIG. 3, the memory apparatus is configured of the memorydevices 3 at intersection points of a number of first wirings (wordlines) 1 and second wirings (bit lines) 6 that are disposed orthogonalto each other in a matrix.

Each memory device 3 has a circular flat shape and a cross-sectionstructure shown in FIG. 2.

Also, each memory device includes the magnetization fixed layer 12 andthe memory layer 14, as shown in FIG. 2.

Thus, the respective memory devices 3 configure a memory cell of thememory apparatus.

Here, in such a memory apparatus, writing should be made at currentlower than a saturated current of the selection transistor. It is knownthat the saturated current of the transistor is lowered as current canbe decreased as the device size gets smaller. In order to decrease thememory apparatus, a spin transfer effectiveness is desirably improved todecrease the current flowing through the memory devices 3.

In order to increase the readout signal, a great magnetoresistive changerate is necessary. It is therefore effective to use the above-describedMTJ structure, i.e., the memory device 3 including a tunnel insulationlayer (tunnel barrier layer) as the intermediate layer between the twomagnetic layers 12 and 14.

In this way, when the tunnel insulation layer is used as theintermediate layer, an amount of current flowing through the memorydevices 3 is limited in order to prevent insulation breakdown of thetunnel insulation layer. In other words, in terms of assuring thereliability of repeated writing of the memory device 3, it is desirablethat the current needed for the spin torque magnetization reversal beinhibited. The current needed for the spin torque magnetization reversalmay be called as a reversal current or a recording current.

Also, as the memory apparatus according to the embodiment is anon-volatile memory apparatus, the information written by the currentshould be stored stably. In other words, the stability (the thermalstability) to thermal fluctuation of the magnetization of the memorylayer 14 should be assured.

If the thermal stability of the memory layer 14 is not assured, adirection of the reversed magnetization may be re-reversed by heat(temperature at an operation environment), which may result in a holdingerror.

The memory devices 3 (STT-MRAMs) in the present memory apparatus can beadvantageous in scaling, i.e., can have a small volume as compared tothe conventional MRAM. However, when the volume is decreased, thethermal stability tends to be decreased as long as other properties arethe same.

When it promotes an increase in the capacity of the STT-MRAM, the memorydevices 3 have smaller volume. Thus, the thermal stability becomes animportant matter.

Therefore, the memory devices 3 (STT-MRAMs) are desirably designed tohave sufficient thermal stability even though the volume may bedecreased, as the thermal stability is a very important property.

<2. Memory Devices in Prior Art and Related Art>

Before the description of the memory devices 3 according to theembodiment, referring to the cross-sectional view of FIG. 4, there isdescribed a schematic configuration of a memory device 3′ in the priorart (STT-MRAM) where a magnetization direction of a memory layer (amagnetization direction in an equilibrium state) is perpendicular to afilm surface.

As illustrated later, the configuration of the memory layers 14 of thememory devices 3 according to the present embodiment is different fromthat of the conventional one. In the description referring to FIG. 4,the memory layer “14” of the memory device 3′ in the prior art is usedas a symbol of the memory layer for convenience.

As shown in FIG. 4, the memory device 3′ in the prior art includes anunderlayer 11, a magnetization fixed layer (also referred to as areference layer) 12 where a direction of magnetization M12 is fixed, anintermediate layer (a non-magnetic layer: a tunnel insulation layer) 13,a memory layer where a direction of magnetization M14 is variable (afree magnetization layer) 14 and a cap layer 15 laminated in this order.

Among them, in the magnetization fixed layer 12, the direction of themagnetization M12 is fixed by a high coercive force, etc. In this case,the direction of the magnetization of the magnetic fixed layer 12 isfixed in a direction perpendicular to the film surface.

In the memory device 3′, information is stored by the direction of themagnetization (a magnetic moment) M14 of the memory layer 14 having auniaxial anisotropy.

Information is written into the memory device 3′ by flowing current to adirection perpendicular to film surfaces of the respective layers (i.e.,a lamination direction of the respective layer) in the memory device 3′to induce the spin torque magnetization reversal.

Here, the spin torque magnetization reversal will be described briefly.

An electron has two types of spin angular momentum. They are defined asupward spin angular momentum and downward spin angular momentum.

Within the non-magnetic body, the electrons having upward spin angularmomentum and the electrons having downward spin angular momentum are thesame in number. In contrast, within a ferromagnetic body, they aredifferent in number.

Firstly, the following case is taken in consideration. The directions ofthe magnetization M12 and the magnetization M14 are non-parallel in twoferromagnetic layers (the magnetization fixed layer 12 and the memorylayer 14) laminated via an intermediate layer 13 and the electrons aremoved from the magnetization fixed layer 12 to the memory layer 14.

The electrons passed through the magnetization fixed layer 12 are spinpolarized, i.e., the electrons having upward spin angular momentum andthe electrons having downward spin angular momentum are different innumber.

When the intermediate layer 13 used as the tunnel insulation layer issufficiently thin, the electrons reach other magnetic body, i.e., thememory layer (the free magnetization layer) 14 before a spinpolarization is relaxed to a non-polarized state (the electrons havingupward spin angular momentum and the electrons having downward spinangular momentum are the same in number).

Signs of the spin polarization in the two ferromagnetic bodies (themagnetization layer 12 and the memory layer 14) are reversed. In orderto decrease energy in the system, a part of the electrons is reversed,i.e., the spin angular momentum is changed. In this case, total angularmomentum of the system should be saved. Counteraction equivalent to thetotal of angular momentum change by turned electrons is provided to themagnetization M14 of the memory layer 14.

When the amount of current, i.e., the number of the electrons passingthrough in a unit time is small, a total number of the turned electronsis small and the angular momentum change generated on the magnetizationM14 of the memory layer 14 is also small. When the amount of the currentis increased, many angular momentum changes can be provided in a unittime.

A time change of the angular momentum is torque. Once the torque exceedsa certain threshold, the magnetization M14 of the memory layer 14 startsa precession movement and becomes stable after 180 degree rotation bythe uniaxial anisotropy of the memory layer 14. In other words, areversal from a non-parallel state to a parallel state takes place.

On the other hand, when the magnetization M14 of the memory layer 14 andthe magnetization M12 of the ferromagnetic body 12 are in the parallelstate and current flows inversely in a direction where the electronsflows through from the memory layer 14 to the magnetic fixed layer 12,the electrons are in turn reflected on the magnetic fixed layer 12.

As the electrons reflected having a spin direction inversed add torqueupon entering into the memory layer 14 to invert the direction of themagnetization M14 of the memory layer 14, the magnetization M12 and themagnetization M14 can be inverted to the non-parallel state.

Note that the amount of current needed to inverse from the parallelstate to the non-parallel state is increased as compared to that fromthe non-parallel state to the parallel state.

As to the inversion from the parallel state to the non-parallel state,an intuitive understanding is difficult. It may be considered that themagnetization M12 of the magnetization fixed layer 12 is fixed andcannot be reversed, and the magnetization M14 of the magnetization fixedlayer 14 is reversed in order to save the angular momentum in the wholesystem.

In this way, 0/1 information can be recorded by flowing currentcorresponding to each polarity at a certain threshold value or more fromthe magnetization fixed layer (the reference layer) 12 to the memorylayer 14 or vice versa.

The information is readout using the magnetoresistance effect similar tothe case of a conventional MRAM.

In other words, current flows in the direction perpendicular to the filmsurfaces of the respective layers (i.e., the lamination direction of therespective layer) similar to the case that the information is recordedas described earlier. It utilizes a phenomenon that electricalresistance shown by the memory device 3′ is changed whether or not thedirection of the magnetization M14 of the memory layer 14 is parallel ornon-parallel to the direction of the magnetization M12 of the magneticfixed layer (the reference layer) 12.

A material used for the intermediate layer 13 used as the tunnelinsulation layer may be metal or an insulator. When the insulator isused in the intermediate layer 13, a higher readout signal (resistivitychange) is provided and the recording can be made at less current. Sucha device is called as the magnetic tunnel junction device (the MTJdevice).

A magnitude of the above-described spin torque is changed by an anglebetween the magnetization M14 of the memory layer 14 and themagnetization M12 of the magnetization fixed layer (reference layer) 12.

“m1” stands for a unit vector representing the direction of themagnetization M14 and “m2” stands for a unit vector representing thedirection of the magnetization M12. The magnitude of the spin torque isproportional to m1×(m1×m2), where “x” represents the cross product ofthe vector.

In general, the magnetization M12 of the magnetization fixed layer 12 isfixed to a magnetization easy axis direction of the memory layer 14. Themagnetization M14 of the memory layer 14 tends to direct to themagnetization easy axis direction of the memory layer 14 itself. In thiscase, the m1 and the m2 make an angle of 0 degree (parallel) or 180degrees (non-parallel).

FIG. 4 illustrates the directions of the magnetization M12 and themagnetization M14 when the angle between the m1 and the m2 is 0 degree.

In this way, when the angle between the m1 and the m2 is 0 degree or 180degrees, the spin torque will not entirely work at all according to theabove-described spin torque equation.

However, in practice, the spin torque functions to induce themagnetization reversal when the angle between the magnetization M14 ofthe memory layer 14 and the magnetization M12 of the magnetization fixedlayer 12 is distant from 0 degree or 180 degrees, as the magnetizationM14 of the memory layer 14 is distributed randomly around themagnetization easy axis direction by the thermal fluctuation.

A time to induce the magnetization reversal (the reversal time) dependson a distance between the magnetization M14 and the magnetization easyaxis direction. The longer the distance between the magnetization M14and the magnetization easy axis, the faster the magnetization isreversed.

As described above, the angle between the magnetization M14 of thememory layer 14 and the magnetization easy axis is distributed randomlyby the thermal fluctuation, the reversal time will be varied widely.

In order to rotate faster even if the magnetization M14 is positionednear (angle) the magnetization easy axis, flowing a large current isnecessary for that.

To this end, the present inventors have been earnestly studied tooperate the memory device at a high speed with a small current.

As a result, the memory layer 14 is configured of a perpendicularmagnetization layer being predominant in perpendicular magnetizationmagnetically connected to an in-face magnetization layer beingpredominant in in-face magnetization via a connecting layer, whereby ithas been discovered that both magnetizations are inclined from adirection perpendicular to the film surface by a magnetic interactionbetween the magnetization of the in-face magnetization layer and themagnetization of the perpendicular magnetization layer (see ReferenceDocuments 1 and 2, for example).

As the magnetization direction of the memory layer 14 is inclined fromthe perpendicular direction, the reversal time can be shortened ascompared to the conventional one that the magnetization direction of thememory layer 14 directs to the perpendicular direction. The reversaltime is required to flow the recording current (reversal current), toreverse the magnetization and to record information. In addition,variations in the reversal time in the conventional configuration can beavoided. In this way, the amount of current upon information recordingcan be decreased and the information can be recorded in a short time,which can provide a memory apparatus being capable of operating at highspeed with less current.

A ferromagnetic layer having the magnetization direction being inclinedfrom the direction perpendicular to the film surface is hereinafterreferred to as an “inclined magnetization layer”.

Reference Document 1: Japanese Patent Application No. 2011-261522

Reference Document 2: Japanese Patent Application No. 2011-261853

A magnetic material for the inclined magnetization layer can be Co—Fe—B.

In general, the ferromagnetic layer used for the memory layer etc. hasvery thin film thickness as compared to a film area. In this case, whenthe magnetization of the ferromagnetic layer directs to the directionperpendicular to the film surface, a great diamagnetic field isprovided. By interaction between the diamagnetic field and themagnetization, diamagnetic field energy (hereinafter referred to as Ed)is increased such that the magnetization cannot stably direct to theperpendicular direction and directs to the in-face direction in theequilibrium state.

Note that the ferromagnetic layer may have perpendicular magneticanisotropy depending on a material and an interface state. In this case,perpendicular magnetic anisotropy energy (hereinafter referred to as Ea)induced by the perpendicular magnetic anisotropy acts on theferromagnetic layer. When the magnetization of the ferromagnetic layerdirects to the direction perpendicular to the film surface, diamagneticfield energy becomes net Ed-Ea.

When the diamagnetic field energy becomes negative, i.e., Ed<Ea, themagnetization can be stable and direct to the perpendicular direction.Hereinafter, the ferromagnetic layer is called as the “perpendicularmagnetization layer being predominant in perpendicular magnetization”.

In contrast, when the diamagnetic field energy becomes positive, i.e.,Ed>Ea, the magnetization cannot be stable and direct to theperpendicular direction. Hereinafter, the ferromagnetic layer is calledas the “in-face magnetization layer being predominant in in-facemagnetization”.

The ferromagnetic layer using Co—Fe—B is generally the in-facemagnetization layer being predominant in the in-face magnetization.

However, Co—Fe—B can be the perpendicular magnetization layer beingpredominant in the perpendicular magnetization, if conditions are met.

Specifically, when the composition and the film thickness of the Co—Fe—Bfilm are within the certain range and the Co—Fe—B film is in contactwith an oxide film (for example, a MgO film), the Co—Fe—B film becomesthe perpendicular magnetization layer being predominant in theperpendicular magnetization (for example, see Japanese PatentApplication No. 2010-200983).

The perpendicular magnetic anisotropy for providing the perpendicularmagnetization is considered to be originated from interfacial anisotropyat an interface between MgO and Co—Fe—B.

When both interfaces of the Co—Fe—B film are in contact with the MgOfilm, i.e., MgO/Co—Fe—B/MgO, the perpendicular magnetic anisotropy willbe increased (for example, see Japanese Patent Application No.2010-201526).

Thus, the ferromagnetic layer using Co—Fe—B can be the in-facemagnetization layer being predominant in the in-face magnetization orthe perpendicular magnetization layer being predominant in theperpendicular magnetization, and is therefore desirable to provide theabove-described inclined magnetization layer.

Referring to the cross-sectional view of FIG. 5, a schematicconfiguration of a prior art memory device 3″ (STT-MRAM) using theinclined magnetization layer will be described.

Although the configuration of the memory layers 14 of the prior artmemory device 3″ is different from that of the present embodiment. Here,the symbol “14” is also used for convenience.

In FIG. 5, the memory device 3″ includes the underlayer 11, themagnetization fixed layer (the reference layer) 12 where the directionof the magnetization M12 is fixed, the intermediate layer (thenon-magnetic layer: the tunnel insulation layer) 13, the memory layerwhere the direction of the magnetization M14 is variable (the freemagnetization layer) 14 and the cap layer 15 laminated in this order.

As described above, the direction of magnetization M12 is fixed in thedirection perpendicular to the film surface (upward in the Figure).

The memory device 3″ has the memory layer 14 in a multilayer structureincluding a ferromagnetic layer and a connecting layer.

Specifically, in this case, the memory layer 14 has a three-layerstructure where a ferromagnetic layer 14 i, a connecting layer 14 c anda ferromagnetic layer 14 p are laminated in this order.

The ferromagnetic layer 14 i is the in-face magnetization layer beingpredominant in the in-face magnetization.

The ferromagnetic layer 14 p is the perpendicular magnetization layerbeing predominant in the perpendicular magnetization.

The ferromagnetic layer 14 i is in contact with the intermediate layer13, and the ferromagnetic layer 14 p is in contact with the cap layer15.

In the above-described configuration, magnetization Mi of theferromagnetic layer 14 i is magnetically connected to magnetization Mpof the ferromagnetic layer 14 p via the connecting layer 14 c.

The information is readout using the magnetoresistance effect similar tothe case of the memory device 3′.

In other words, current flows in the direction perpendicular to the filmsurfaces of the respective layers (i.e., the lamination direction of therespective layer) similar to the case that the information is recordedas described earlier. It utilizes a phenomenon that electricalresistance shown by the memory device 3″ is changed depending on arelative angle between the magnetization M12 of the magnetic fixed layer12 and the magnetization Mi of the ferromagnetic layer 14 i.

In the case of the prior art memory device 3″ shown in FIG. 5, as themagnetization Mi is inclined from the perpendicular direction, therelative angle of the magnetization Mi is increased and the amplitude ofthe readout signal is smaller than that in the memory device 3′ in theprior art using the perpendicular magnetization film.

FIG. 6 shows a further detail of the configuration of the memory layer14 of the prior art memory device 3″ shown in FIG. 5.

For convenience, the connecting layer 14 c is omitted.

Firstly, the memory layer 14 of the memory device 3″ is in a cylindricalshape.

Here, in order to describe the directions of the magnetization Mi andthe magnetization Mp, angles θ1 and θ2 are defined as follows: In otherwords, an axis penetrating through the memory layer 14 in theperpendicular direction is defined as a perpendicular axis aV. An anglebetween the magnetization Mi and the perpendicular axis aV is defined asθ1. An angle between the magnetization Mp and the perpendicular axis aVis defined as θ2.

As described above, the magnetization Mi is predominant in the in-facemagnetization and the magnetization Mp is predominant in theperpendicular magnetization.

Accordingly, when the magnetization direction is inclined from theperpendicular axis aV by connecting via the connecting layer 14 c, theangle θ1 will be greater than the angle θ2. In other words, themagnetization Mi is greatly inclined from the perpendicular axis aV.

The greater the relative angle between the magnetization M12 of themagnetic fixed layer 12 the magnetization Mi of the ferromagnetic layer14 i is, the greater the spin torque is. By the above-describedconfiguration of the memory layer 14 in the prior art, the magnetizationcan be reversed at a higher speed.

However, the inclination of the magnetization Mi from the perpendicularaxis aV leads to a side effect that the amplitude of the readout signalis decreased.

As understood from the description so far, the amplitude of the readoutsignal equals to a difference between electrical resistance values ofthe memory device in the parallel state and the memory device in thenon-parallel state.

In the memory device 3′ in the prior art, the angle between themagnetization M12 and the magnetization Mi is about 0 degree in theparallel state, and the angle between the magnetization M12 and themagnetization Mi is about 180 degrees in the non-parallel state. Incontrast, in the prior art memory device 3″, the magnetization Mi isinclined from the perpendicular axis aV as described above. Therefore,the angle between the magnetization M12 and the magnetization Mi exceeds0 degree. As a result, the electrical resistance value in the parallelstate in the prior art is greater than that of the memory device 3′ inthe prior art. Also in the non-parallel state, the magnetization Mi isinclined from the perpendicular axis aV. Therefore, the angle betweenthe magnetization M12 and the magnetization Mi is less than 180 degrees.As a result, the electrical resistance value in the non-parallel statein the prior art is smaller than that of the memory device 3′ in theprior art.

Consequently, the difference between the electrical resistance values ofthe prior art memory device 3″ in the parallel state and in thenon-parallel state is smaller than that in the memory device 3′ in theprior art. This shows that the amplitude of the readout signal in theprior art is smaller than that in the conventional one.

In view of the problems of the prior art, according to the embodiment,the magnetization of the memory layer is directed to the perpendiculardirection in the equilibrium state where no current flows through thememory device. Upon the recording, before the recoding current flows,current smaller than the recording current flows through the memorydevice to change the memory layer to a standby state. In other words,the direction of the magnetization of the memory layer is changed fromthe perpendicular direction to the inclined direction.

In this manner, both of the magnetization reversal at a high speed andthe great readout signal can be provided.

<4. First Embodiment>

Hereinafter, a specific embodiment of the present technology will bedescribed.

FIG. 7 are explanatory views of a memory device 3 according to a firstembodiment.

In FIG. 7, FIG. 7A shows a schematic configuration (cross-sectionalview) of the memory device 3 in the first embodiment.

In the following description, components already described are denotedby the same reference numerals, and thus detailed description thereofwill be hereinafter omitted.

In FIG. 7A, the memory device 3 includes the underlayer 11, themagnetization fixed layer 12, the intermediate layer 13, the memorylayer 14 and the cap layer 15 laminated similar to those of the priorart memory device 3″. The memory layer 14 of the memory device 3includes the ferromagnetic layer 14 i, the connecting layer 14 c and theferromagnetic layer 14 p are laminated similar to those in the priorart.

In this embodiment, Co—Fe—B is used for the ferromagnetic layer 14 i andthe connecting layer 14 c.

However, the memory device 3 according to the embodiment is differentfrom the memory device 3″ in that the memory layer 14 is configured suchthat the magnetizations Mi and Mp direct to the perpendicular directionin the equilibrium state where no current flows through the memorydevice 3.

This can be achieved by increasing an intensity (hereinafter referred toas a connecting intensity) of the magnetic interaction between themagnetization of the ferromagnetic layer 14 i (the in-face magnetizationlayer) and the magnetization of the ferromagnetic layer 14 p (theperpendicular magnetization film) via the connecting layer 14 c. Inother words, in the memory device 3 according to the embodiment, theconnecting intensity between the ferromagnetic layer 14 i and theferromagnetic layer 14 p is set such that the magnetizations Mi and Mpdirect to the perpendicular direction in the equilibrium state. Theconnecting intensity between the ferromagnetic layer 14 i and theferromagnetic layer 14 p can be adjusted by the film thickness of theconnecting layer 14 c.

The directions of the magnetizations Mi and Mp depend on the connectingintensity. When the connecting intensity exceeds a certain threshold,the directions of the magnetizations Mi and Mp are matched in the samedirection. The directions of both may be in the in-face direction or theperpendicular direction. By increasing the perpendicular magneticanisotropy of the perpendicular magnetization layer being predominant inthe perpendicular magnetization, it is possible to direct both in theperpendicular direction.

In this way, by increasing the connecting intensity in the equilibriumstate above the threshold value, both magnetizations can direct to theperpendicular direction.

This allows the amplitude of the readout signal to be increased to thesimilar level of the memory device 3′ in the prior art using theperpendicular magnetization film.

FIG. 7B schematically shows that a standby current Is flows through thememory device 3 to change the state of the memory device 3 into astandby state.

As shown in FIG. 7B, the standby current Is flows in a laminationdirection of the memory device. When the standby current Is flows, Jouleheat is generated in the memory device 3 and the memory layer 14 isincreased in temperature. The connecting intensity depends on thetemperature. As the temperature is increased, the connecting intensitytends to be decreased.

At this time, when the connecting intensity in the standby state islower than the threshold value, the directions of the magnetizations Miand Mp are changed from the perpendicular direction to the inclineddirection.

According to the embodiment, the memory device 3 is changed to thestandby state, and the recording current flows to store the information.As described above, the memory layer 14 has the inclined magnetizationin the standby state. The recording current flows in the standby stateto store the information, thereby reversing the magnetization at a highspeed similar to the memory device 3″ in the prior art.

On the other hand, according to the embodiment, as the magnetizations Mpand Mi direct to the perpendicular direction in the equilibrium state,the amplitude of the readout signal will not be decreased beingdifferent from that in the prior art.

Examples of the materials used for each of lamination films of thememory device 3 will be described. A description about the componentsalready described as to the memory device 3″ in the prior art will behereinafter omitted.

For the connecting layer 14 c, a non-magnetic metal such as Ta, Ru andthe like can be used.

For the intermediate layer (the non-magnetic layer) 13 between themagnetization fixed layer 12 and the memory layer 14, an insulationmaterial (a variety of oxides, etc.) for forming the tunnel insulationlayer or a non-magnetic metal used between the magnetic layers of themagnetoresistive effect device can be used.

When the insulation material is used for the intermediated layer 13, thehigher readout signal (the resistivity change) is provided and therecording can be made at less current, as described above.

In the first embodiment, in order to provide the ferromagnetic layer 14p that is the perpendicular magnetization layer being predominant in theperpendicular magnetization, an oxide such as MgO can be used for thecap layer 15. Although not shown, by laminating the non-magnetic metalsuch as Ta, Ru and the like on the MgO layer in the cap layer 15,electric conductivity is desirably increased.

For the magnetic fixed layer 12, a variety of magnetic materials used inthe memory device of the conventional STT-MRAM can be used.

For example, NiFe, TePt, CoPt, TbFeCo, GdFeCo, CoPd, MnBi, MnGa, PtMnSb,Co—Fe—B, Co—Cr based materials etc. can be used. Other than thesematerials, the magnetic materials can be used.

Referring to FIG. 8, changes from the equilibrium state to the standbystate and to the recording state will be specifically described.

FIG. 8 is a conceptual diagram between current flowing in a laminationdirection of the memory device 3 and a time change of perpendicularcomponents (mz) of magnetization Mi and magnetization Mp.

In a time domain T1, the memory layer 14 is in the equilibrium state andthe perpendicular components mz of magnetization Mi and magnetization Mpare “1”, i.e., in the perpendicular direction.

Before a recording operation, the standby current Is flows to the memorydevice 3 from an end point of the time domain T1 to change to thestandby state. Then, as the memory device 3 is increased in temperature,the connecting intensity is decreased and the perpendicular componentsof the magnetizations Mi and Mp are decreased from “1” (time domain T2).Thereafter, the memory device 3 is uniform in temperature. Thedirections of the magnetizations Mi and Mp are determined by theconnecting intensity at that time (time domain T3). In other words, astable state can be provided as the standby state.

In this way, after the stable standby state is provided (i.e., at anymoment within the time domain T3), the recording current flows toconduct actual recording.

FIG. 9 is a block diagram showing an overall configuration of the memoryapparatus according to the embodiment, which includes the configurationthat the memory device 3 is in the standby state and the information isthen stored as described above.

As illustrated in FIG. 3, the memory apparatus according to theembodiment is configured of the memory devices 3 at intersection pointsof the word lines 1 and the bit lines 6 that are disposed orthogonal toeach other in a matrix.

In FIG. 9, symbols 1 a, 1 b, 1 c, 1 d . . . are added to a plurality ofthe word lines 1 from the above in FIG. 9 and symbols 6 a, 6 b, 6 c, 6 d. . . are added to a plurality of the bit lines 6 from the left in FIG.9, for convenience.

The memory apparatus according to the embodiment includes a word linedriving circuit 51 for driving the word lines 1, a bit line drivingcircuit 52 for driving the bit lines 6 in accordance with input data,and a control unit 50.

The control unit 50 controls a driving timing of the word lines 1 by theword line driving circuit 51, and also controls a driving timing of thebit lines 6 by the bit line driving circuit 52. Specifically, while oneword line 1 is driven (selected) by the word line driving circuit 51,the bit lines 6 are driving in accordance with the input data by the bitline driving circuit 52. Such a control is sequentially executed bychanging the word line 1 selected. In this way, data can be stored onthe desired memory device 3.

At this time, the control unit 50 controls such that the standby currentshown in FIG. 10 flows from the bit line driving circuit 52 to each bitline 6 corresponding to data recording. Specifically, before a recordingcurrent Iw flows, the bit line driving circuit 52 is controlled to flowthe standby current Is. As apparent from FIG. 10, the standby current Isis lower than the recording current Iw (comparison by an absolutevalues).

Although only one polarity (positive polarity) is shown as polarities ofthe standby current Is and the recording current Iw in FIG. 10, 0/1 canbe recorded by changing the direction of the current flowing through thememory device, as described above. For example, when the polarity shownin FIG. 10 corresponds to wiring data “1”, current having the polarityreversed from FIG. 10 flows to write data “0”.

As a supply period of the standby current Is (a period from the standbycurrent Is is started to be flowed to the recording current Iw isstarted to be flowed) shown as “Ts” in FIG. 10A, it is desirable toassure the period for maintaining temperature of the memory device 3constant and stabilizing the directions of the magnetizations Mi and Mpafter the standby current Is is started to be fed, as understood fromFIG. 8.

Note that this does not deny that the recording current Iw is started tobe fed before the directions of the magnetizations Mi and Mp arestabilized. It is possible to flow the recording current Iw to start therecording operation before the standby state is stabilized (at anymoment within the time domain T2 shown in FIG. 8).

<5. Second Embodiment>

Subsequently, referring to FIG. 11, a memory device 20 according to asecond embodiment will be described.

In FIG. 11, FIG. 11A is a schematic configuration view (cross-sectionalview) of the memory device 20. FIG. 11A shows the magnetizations Mi andMp in the equilibrium state of the memory device 20 and themagnetization M12 of the magnetization fixed layer 12.

The memory device 20 according to the second embodiment is differentfrom the memory device 3 according to the first embodiment in that theorder of the memory layers 14 is different. Specifically, theferromagnetic layer 14 p, the connecting layer 14 c and theferromagnetic layer 14 i are laminated in this order. In this case, theferromagnetic layer 14 p is in contact with the intermediate layer 13,and the ferromagnetic layer 14 i is in contact with the cap layer 15.

In order to provide the ferromagnetic layer 14 p that is theperpendicular magnetization layer being predominant in the perpendicularmagnetization, an oxide such as MgO can be used for the intermediatelayer 13.

In the memory device 20 having the above-described configuration, thespin torque is determined by the relative angle between themagnetization M12 of the memory layer 12 and the magnetization Mp of theferromagnetic layer 14 p.

FIG. 11B shows the magnetization Mi of the ferromagnetic layer 14 i andthe magnetization Mp of the ferromagnetic layer 14 p when the standbycurrent Is flows to the memory device 20 to a standby state.

In the memory device 20, the angle θ2 (the angle between themagnetization Mp and the perpendicular axis aV) is smaller than theangle θ1 (the angle between the magnetization Mi and the perpendicularaxis aV). Accordingly, the spin torque in the memory device 20 issmaller than that of the memory device 3 according to the firstembodiment. However, as compared to the memory device 3′ in the priorart, the direction of the magnetization (the magnetization in thestandby state) of the memory layer 14 is inclined, thereby allowing themagnetization reversal at the higher speed upon recording operation.

For confirmation, the memory apparatus according to the secondembodiment includes a memory device 20 instead of the memory device 3 inthe memory apparatus having the configuration shown in FIG. 9 earlier.

Also, the memory apparatus according to the second embodiment includingthe above-described memory device 20 can prevent the amplitude of thereadout signal to be decreased while the memory apparatus can beoperated at high speed with less current.

<6. Simulation Results>

In order to prove the effectiveness of the memory devices (3, 20)according to the respective embodiments as described above, themagnetization reversal was simulated by a macro spin model.

FIG. 12 show simulated results about time changes of the perpendicularcomponents (mz) of the magnetization when the current flows.

FIG. 12A shows the simulated results about the memory device 3′ in theprior art, and FIG. 12B shows the simulated results about the memorydevice according to the embodiment. In the FIG. 12B, as “the memorydevice according to the embodiment”, the memory device 20 according tothe second embodiment was used.

In FIG. 12A and FIG. 12B, a horizontal axis represents an elapsed timeafter the current flows, and a vertical axis represents theperpendicular components mz of magnetization. An upward direction is 1,and a downward direction is −1. A current flowing time (also referred toas a current supply time) was 20 nm. An original time point is when therecording current is started to be flowed to the memory layer 14 in thestandby state.

In the memory device 3′ in the prior art, the magnetization M14 of thememory layer 14 directs to the perpendicular direction in theequilibrium state. As the spin torque does not function as it is,calculation was made by tilting 0.01 degrees from the vertical axis aV.

In a calculation example shown in FIG. 12B, the magnetization M14 of thememory layer 14 directs to the direction at 29 degrees from the verticaldirection in the standby state, and the magnetization Mi of theferromagnetic layer 14 i directs to the direction at 73 degrees from thevertical direction in the standby state.

In the memory device 3′ in the prior art, as the direction of themagnetization M14 is almost in the direction perpendicular to the filmsurface, the spin torque gets smaller and a change in the magnetizationmotion gets smaller to the time change. Consequently, as shown in a timedomain T11 of FIG. 12A, there is a domain where the magnetizationdirection is almost not changed, even if current flows.

Here, a length of the time domain T11 is changed every recordingoperation depending on an initial angle of the magnetization.Accordingly, a time for the magnetization reversal is varied, and asufficiently long recording time is necessary for reversing themagnetization with certainty.

After the time domain T11, the direction of the magnetization M14 israpidly changed to induce the magnetization reversal (a time domainT12). After a time domain T13 where current supply is continued, thecurrent becomes zero in a time domain T14.

In contrast, in the memory device according to the embodiment, themagnetization Mp of the ferromagnetic layer 14 p is inclined from thedirection perpendicular to the film surface in the standby state.Accordingly, the magnetization Mp of the ferromagnetic layer 14 p issubjected to some spin torque once the recording current flows torapidly start the reversal operation (time domain T15). At this time, asthe magnetization Mi of the ferromagnetic layer 14 i is magneticallyconnected to the magnetization Mp, a reversal motion is started in tunewith the motion of the magnetization Mp.

Thus, according to the memory device of the embodiment, themagnetization reversal at a high speed is possible.

In the case of the memory device of the embodiment, there is no timedomain where the change in the magnetization motion is small like thetime domain T11 shown in FIG. 12A. This means that not only the memorydevice of the embodiment can shorten the time to flow the recordingcurrent, and but also the variations in the reversal time can bedecreased.

Here, during a time domain T16 where the current supply is continued,the directions of the magnetization Mp and the magnetization Mi are offfrom the perpendicular direction due to an effect of a temperatureincrease and the spin torque.

By the calculation from FIG. 12B, an angle of the magnetization Mp is156 degrees and an angle of the magnetization Mi is 112 degrees.

When the current becomes zero in a time domain T17, the connectingintensity returns to the original magnitude and it changes to theequilibrium state directing to the perpendicular direction.

From the result, it is also shown that the memory device of theembodiment can prevent the amplitude of the readout signal to bedecreased while the high speed writing is possible with less current, asthe magnetization M14 of the memory layer 14 directs to theperpendicular direction in the equilibrium state.

Although in the simulation in FIG. 12, the memory device 20 was used asthe memory device according to the embodiment, an improvement effect canbe provided when the memory device 3 in the first embodiment is used ascompared to the memory device 3′ in the prior art or the memory device3″ in the related art.

<7. Procedure for Shortening Recording Time>

As understood from the description, the memory apparatus of theembodiment changes the state of the memory device to the standby statebefore the recording operation. While the time required for therecording operation itself is shortened, the time to change to thestandby state will be required. In order to shorten the time, aprocedure for performing the recording operation in a plurality of thememory devices can be employed as described later.

FIG. 13 is an explanatory view for the procedure for shortening therecording time.

In FIG. 13, a continuous recording by the memory devices 3 a, 3 b, 3 cand 3 d in this order is simulated, and current waveforms to be suppliedto the memory devices 3 a to 3 d are shown. Herein, the memory devices 3a to 3 d are the memory devices 3 positioned serially on a word line 1.

The conditions are as follows: the word line 1 at which the memorydevices 3 a to 3 d are positioned is HIGH, and current is capable offlowing through the memory devices 3.

On the condition that the word line 1 is selected and the current iscapable of flowing through the memory devices 3 a to 3 d, the currenthaving the waveforms shown in FIG. 13 is supplied to respective bitlines 6.

Specifically, the current is supplied to the respective bit lines 6 suchthat a period (Tw) for flowing the recording current Iw to the memorydevices 3 to be recorded and a period (Ts) for flowing the standbycurrent Is to the memory devices 3 to be recorded are overlapped.

Here, if the four memory devices 3, i.e., the memory devices 3 a to 3 d,independently perform the recording operation, it requires a time of4×(Ts+Tw). However, the recording in a pipeline method shown in FIG. 13can shorten the required time to Ts+4×Tw.

In this way, an overhead period required to change to the standby statebefore the recording operation can be decreased by the continuousrecording where the period for flowing the standby current and theperiod for flowing the recording current are overlapped.

The above-described recording in the pipeline method can be achieved bythe control unit 50 shown in FIG. 9 earlier that generates a timingsignal and supplies it to the bit line driving circuit 52. The timingsignal is for overlapping the period where the recording current Iwflows to the memory devices 3 to be recorded and the period where thestandby current Is to the memory devices 3 to be recorded, as describedabove.

Although FIG. 13 illustrate the case that the memory devices 3 are used,the recording in the pipeline method can also be performed using thememory devices 20 to shorten the recording time.

<8. Alternative Embodiment>

While the present technology is described herein with reference toillustrative embodiments, it should be understood that the presenttechnology is not limited thereto.

For example, although as the material for providing the Co—Fe—B filmwith the perpendicular magnetic anisotropy, an oxide such as MgO iscited, a variety of materials other than the oxide can be used.

The material of the connecting layer 14 c is not limited to Ta and Ru,and may be such that a magnetic connection can be generated between theferromagnetic layers, e.g., Zr, V, Cr, Nb, Mo, W, and Mg.

The underlayer 11 or the cap layer 15 may be a single material or alaminated structure of a plurality of materials.

The magnetization fixed layer 12 may be a monolayer structure or alaminated Feripin structure including two layers of the ferromagneticlayer and the non-magnetic layer. In addition, an antiferromagnetic filmmay be added to a film of the Feripin structure.

In the present technology, a film structure of the memory device may besuch that the memory layer is disposed at upper side or a lower side ofthe magnetization fixed layer.

In addition, a so-called dual structure where the magnetization layersare disposed at upper and lower of the memory layer may be employed.

The memory devices 3, 20 according to the present technology are eachconfigured of a magnetoresistive effect device such as a TMR device. Themagnetoresistive effect device such as a TMR device can be applied notonly to the above-described memory apparatus, but also to a variety ofelectronic devices and electric devices including a magnetic head, ahard disk drive to which the magnetic head is mounted, an integratedcircuit chip, and a variety of electronic devices and electric devicesincluding a personal computer, a mobile terminal, a mobile phone and amagnetic sensor device.

As an example, FIG. 14A and FIG. 14B show an application of theabove-described memory devices 3, 20, i.e., a magnetoresistive effectdevice 101 to a combined magnetic head 100. FIG. 14A is a perspectiveview partly cutting away to show an internal structure. FIG. 14B is asectional view of the combined magnetic head 100.

The combined magnetic head 100 is a magnetic head used for a hard diskapparatus etc., and includes a substrate 122, the magnetoresistiveeffect magnetic head according to the present technology formed on thesubstrate 122, an inductive magnetic head laminated on themagnetoresistive effect magnetic head. The magnetoresistive effectmagnetic head functions as a playback head, and the inductive magnetichead functions as a recording head. In other words, the combinedmagnetic head 100 is configured by combining the playback head and therecording head.

The magnetoresistive effect magnetic head mounted on the combinedmagnetic head 100 is a so-called MR head, and includes a first magneticshield 125 formed via an insulation layer 123 on the substrate 122,magnetoresistive effect device 101 formed via the insulation layer 123on the first magnetic shield 125, and a second magnetic shield 127formed via the insulation layer 123 on the magnetoresistive effectdevice 101. The insulation layer 123 is composed of an insulationmaterial such as Al2O3 and SiO2.

The first magnetic shield 125 is for magnetically shielding a lowerlayer of the magnetoresistive effect device 101, and is composed of asoft magnetic material such as Ni—Fe. On the first magnetic shield 125,the magnetoresistive effect device 101 is formed via the insulationlayer 123.

The magnetoresistive effect device 101 functions as a magnetosensitivedevice for detecting a magnetic signal from a magnetic recording mediumin the magnetoresistive effect magnetic head. The magnetoresistiveeffect device 101 has the film configuration (the layer structure)similar to that of the above-described memory devices 3, 20.

The magnetoresistive effect device 101 is formed in a substantiallyrectangular shape such that one side face is exposed to an opposite faceof the magnetic recording medium. At both ends of the magnetoresistiveeffect device 101, bias layers 128, 129 are disposed. Connectingterminals 130, 131 are formed to connect to the bias layers 128, 129.Via the connecting terminals 130, 131, sense current is supplied to themagnetoresistive effect device 101.

At upper parts of the bias layers 128, 129, the second magnetic shieldlayer 127 is disposed via the insulation layer 123.

The above-described inductive magnetic head laminated on themagnetoresistive effect magnetic head includes a magnetic core composedof the second magnetic shield 127 and an upper layer core 132, and athin film coil 133 formed to wind the magnetic core.

The upper layer core 132 forms a closed magnetic path together with thesecond magnetic shield 122 to be the magnetic core of the inductivemagnetic head, and is composed of a soft magnetic material such asNi—Fe. The second magnetic shield 127 and the upper layer core 132 areformed such that front ends thereof are exposed to the opposite face ofthe magnetic recording medium and back ends thereof are in contact withthe second magnetic shield 127 and the upper layer core 132. The frontends of the second magnetic shield 127 and the upper layer core 132 areformed at the opposite face of the magnetic recording medium such thatthe second magnetic shield 127 and the upper layer core 132 are apartfrom each other at a predetermined gap g.

In other words, in the combined magnetic head 100, the second magneticshield 127 not only magnetically shields an upper layer of amagnetoresistive effect device 126, but also functions as the magneticcore of the inductive magnetic head. The magnetic core of the inductivemagnetic head is composed of the second magnetic shield 127 and theupper layer core 132. The gap g will be a magnetic gap for recording inthe inductive magnetic head.

On the second magnetic shield 127, the thin film coil 133 buried intothe insulation layer 123 is formed. The thin film coil 133 is formed towind the magnetic core including the second magnetic shield 127 and theupper layer core 132. Although not shown, both ends of the thin filmcoil 133 are exposed externally. Terminals formed on the both ends ofthe thin film coil 133 will be external connection terminals of theinductive magnetic head. In other words, when the magnetic signal isrecorded to the magnetic recording medium, recording current is suppliedto the thin film coil 132 from the external connection terminals.

As described above, the laminated structure as the memory deviceaccording to the present technology can be applied as the playback headfor the magnetic recording medium, i.e., the magnetosensitive device fordetecting the magnetic signal from the magnetic recording medium.

According to the present technology, the memory device used in thememory apparatus is not limited to the illustrated configuration, i.e.,the first ferromagnetic layer, the connecting layer and the secondferromagnetic layer are laminated in this order, one of the firstferromagnetic layer and the second first ferromagnetic layer is thein-face magnetization layer being predominant in the in-facemagnetization, and the other is the perpendicular magnetization layerbeing predominant in the perpendicular magnetization.

As understood by the above description, in the memory device having sucha configuration, depending on the setting of the connecting intensitybetween the first ferromagnetic layer and the second ferromagnetic layervia the connecting layer, the magnetization of the memory layer isdirected to the perpendicular direction in the equilibrium state and thestandby current flows, the magnetization direction of the memory layeris inclined from the perpendicular direction. The memory device used inthe memory apparatus according to the present technology is not limitedthereto as long as the memory device has the following configuration. Inother words, the memory device has a layer structure at least includinga memory layer where a direction of magnetization is changedcorresponding to information, a magnetic fixed layer where the directionof the magnetization is fixed, and an intermediate layer made of anon-magnetic body disposed between the memory layer and the magneticfixed layer; current being capable of flowing in a lamination directionof the layer structure, the magnetization of the memory layer directs toa perpendicular direction in an equilibrium state, and the direction ofthe magnetization of the memory layer is changed from the perpendiculardirection to the inclined direction by flowing standby current.

The present technology may have the following configurations.

(1) A memory apparatus, including:

a memory device having:

a layer structure at least including a memory layer where a direction ofmagnetization is changed corresponding to information, a magnetic fixedlayer where the direction of the magnetization is fixed, and anintermediate layer made of a non-magnetic body disposed between thememory layer and the magnetic fixed layer; current being capable offlowing in a lamination direction of the layer structure;

a wiring for supplying the memory device with current flowing to thelamination direction; and

a memory control unit for storing information by flowing standby currentat a predetermined level to the memory device via the wiring to inclinethe magnetization direction of the memory layer from the directionperpendicular to a film surface and flowing recording current that ishigher than the standby current via the wiring to change themagnetization direction of the memory layer.

(2) The memory apparatus according to (1) above, in which

a plurality of the memory devices are arranged, and the memory controlunit controls a current supply to the memory device via the wiring suchthat a period for flowing the recording current to the memory device tobe recorded and a period for flowing the standby current to the memorydevice to be recorded are overlapped.

(3) The memory apparatus according to (1) or (2) above, in which

the memory device has a cap layer, and

in the memory layer,

the first ferromagnetic layer, the connecting layer and the secondferromagnetic layer are laminated in this order,

the first ferromagnetic layer is magnetically connected to the secondferromagnetic layer via the connecting layer,

the first ferromagnetic layer is in contact with the intermediate layer,

the second ferromagnetic layer is in contact with the cap layer,

one of the first ferromagnetic layer and the second first ferromagneticlayer is the in-face magnetization layer being predominant in thein-face magnetization, and

the other is the perpendicular magnetization layer being predominant inthe perpendicular magnetization.

(4) The memory apparatus according to (3) above, in which

in the memory layer, a connecting intensity between the firstferromagnetic layer and the second ferromagnetic layer via theconnection layer is set such that both magnetizations of the firstferromagnetic layer and the second ferromagnetic layer direct to theperpendicular direction in an equilibrium state where no current in thelamination direction flows to the memory device.

(5) The memory apparatus according to (4) above, in which

the first ferromagnetic layer is the in-face magnetization layer, andthe second ferromagnetic layer is the perpendicular magnetization layer.

(6) The memory apparatus according to (5) above, in which

while the standby current flows, an angle between the magnetization ofthe first ferromagnetic layer and the direction perpendicular to thefilm surface is greater than an angle between the magnetization of thesecond ferromagnetic layer and the direction perpendicular to the filmsurface.

(7) The memory apparatus according to (4) above, in which

the first ferromagnetic layer is the perpendicular magnetization layer,and the second ferromagnetic layer is the in-face magnetization layer.

(8) The memory apparatus according to (7) above, in which

while the standby current flows, an angle between the magnetization ofthe first ferromagnetic layer and the direction perpendicular to thefilm surface is smaller than an angle between the magnetization of thesecond ferromagnetic layer and the direction perpendicular to the filmsurface.

(9) The memory apparatus according to any one of (1) to (8) above, inwhich the intermediate layer is a tunnel insulation layer.

(10) The memory apparatus according to any one of (3) to (9) above, inwhich the cap layer includes an oxide layer.

(11) The memory apparatus according to any one of (3) to (10) above, inwhich the first ferromagnetic layer and the second ferromagnetic layerincludes Co—Fe—B layers.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

DESCRIPTION OF SYMBOLS

-   1 gate electrode-   2 device separation layer-   3, 20 memory device-   4 contact layer-   6 bit line-   7 source region-   8 drain region-   9 wiring-   10 semiconductor substrate-   11 underlayer-   12 magnetization fixed layer-   13 intermediate layer-   14 memory layer-   14 i, 14 p ferromagnetic layer-   14 c connection layer-   15 cap layer (perpendicular magnetic anisotropy layer)

The invention claimed is:
 1. A memory system, comprising: a memory areaconfigured to include a plurality of memory cells; a driving areaconfigured to drive the memory cells; and a control area configured tosupply a standby current to the memory area before the memory arearecords data; a plurality of word lines is crossing to a plurality ofbit lines via the plurality of memory cells; and wherein each of thememory cells includes a memory layer, a magnetic fixed layer, anintermediate layer including a non-magnetic material provided betweenthe memory layer and the magnetic fixed layer.
 2. The memory systemaccording to claim 1, wherein a current is configured to flow in alamination direction between the memory layer and the magnetic fixedlayer.
 3. The memory system according to claim 2, further comprising theplurality of the word lines and the bit lines configured to supply thecurrent to the memory area.
 4. The memory system according to claim 3,wherein the control area is configured to control a current supply tothe memory area via the plurality of the word lines and the bit lineswhen a period for flowing a recording current to the memory area to berecorded and a period for flowing the standby current to the memory areato be recorded are overlapped.
 5. The memory system according to claim4, wherein the control area is configured to store information byflowing the standby current at a predetermined level to the memory areato incline the magnetization direction of the memory layer from adirection perpendicular to a film surface and flowing the recordingcurrent that is higher than the standby current to change themagnetization direction of the memory layer.
 6. The memory systemaccording to claim 5, wherein each of the memory cells includes a caplayer, and the memory layer includes: a first ferromagnetic layer, aconnecting layer and a second ferromagnetic layer being laminated inthis order, wherein the first ferromagnetic layer is magneticallyconnected to the second ferromagnetic layer via the connecting layer,wherein the first ferromagnetic layer is in contact with an intermediatelayer, wherein the second ferromagnetic layer is in contact with the caplayer, wherein one of the first ferromagnetic layer and the second firstferromagnetic layer is an in-face magnetization layer being predominantin the in-face magnetization, and wherein the other is a perpendicularmagnetization layer being predominant in the perpendicularmagnetization.
 7. The memory system according to claim 6, wherein in thememory layer, a connecting intensity between the first ferromagneticlayer and the second ferromagnetic layer via the connection layer is setsuch that both magnetizations of the first ferromagnetic layer and thesecond ferromagnetic layer direct to the perpendicular direction in anequilibrium state where no current in the lamination direction flows tothe memory area.
 8. The memory system according to claim 6, wherein thefirst ferromagnetic layer is the in-face magnetization layer, and thesecond ferromagnetic layer is the perpendicular magnetization layer. 9.The memory system according to claim 8, wherein while the standbycurrent flows, an angle between the magnetization of the firstferromagnetic layer and the direction perpendicular to the film surfaceis greater than an angle between the magnetization of the secondferromagnetic layer and the direction perpendicular to the film surface.10. The memory system according to claim 6, wherein the firstferromagnetic layer is the perpendicular magnetization layer, and thesecond ferromagnetic layer is the in-face magnetization layer.
 11. Thememory system according to claim 10, wherein while the standby currentflows, an angle between the magnetization of the first ferromagneticlayer and the direction perpendicular to the film surface is smallerthan an angle between the magnetization of the second ferromagneticlayer and the direction perpendicular to the film surface.
 12. Thememory system according to claim 6, wherein the cap layer includes anoxide layer.
 13. The memory system according to claim 6, wherein thefirst ferromagnetic layer and the second ferromagnetic layer includeCo—Fe—B layers.
 14. The memory system according to claim 1, wherein theintermediate layer includes a tunnel insulation layer.